Question

I am trying to implement a ToEnumerable property on an external type that does not implement it. I can’t quite get the code to work.

So I dumbed it down to adding a untyped GetEnumerator property, and added the code for ToComparable for guidance. However, I have no idea on how to store the mutable state for the counter.

Is the pb the anonymous class ?

How would you do it ?

open System
open System.Collections
open System.Collections.Generic

type Bloomberglp.Blpapi.Element with
     //**WORKS OK**
     member this.ToComparable:IComparer<Bloomberglp.Blpapi.Element> =   { 
        new IComparer<Bloomberglp.Blpapi.Element> with 
           member this.Compare(x, y) = x.NumValues.CompareTo(y.NumValues) 
     }

     //**WORKS (sort of) OK without storing the state**
     member this.GetEnumerator2:IEnumerator =  {
        //let mutable i =0
        new IEnumerator with
              member this2.Reset() = 
                 i <- 0;
                 ()
              member this2.MoveNext() = 
                 if i < n then 
                    i <- i + 1
                    true
                 else
                    false
              member this2.Current 
                 with get() =
                    this.GetElement(0) :> obj
     }

Answer 1

Assuming NumValues is the count, you could do something like this:

type Bloomberglp.Blpapi.Element with
  member this.GetEnumerator() = 
    (Seq.init this.NumValues this.GetElement).GetEnumerator()

This returns IEnumerator<'T> where 'T is the return type of GetElement.